1. Technical Field
The present invention relates to a light emitting diode (LED) driving apparatus, and more particularly, to an LED driving apparatus for driving an LED used as a backlight of a liquid crystal display.
2. Description of the Related Art
Generally, a liquid crystal display has characteristics such as light weight, a thin thickness, low power consumption, and the like, such that application fields thereof have increased. In accordance with this trend, the liquid crystal display has been used in an office automation device, an audio/video device, and the like.
Since the liquid crystal display as described above does not perform self-lighting, it requires a separate light source called a backlight. As this backlight, a light emitting diode (hereinafter, referred to as an ‘LED’), a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), or the like, has been used.
Recently, a backlight light source using the LED has been mainly used. The LED backlight light source is environment-friendly and has a high speed response, such that it may be effectively used for a video signal stream.
FIG. 1 is a circuit diagram schematically showing an LED driving apparatus according to the related art.
Referring to FIG. 1, the LED driving apparatus 1 is formed of a direct current (DC)-DC converter 10 including a transformer 12 switching power input from a control circuit 11 to a primary side thereof to induce and output the power to a secondary side thereof, a rectifying diode D1 rectifying voltage output from the secondary side of the transformer 12, and a smoothing capacitor C1 smoothing the rectified voltage.
The LED driving apparatus 1 converts alternate current power applied thereto into DC power by an operation of the DC-DC converter 10 and provides the converted DC power to LEDs D2 to D4, thereby allowing desired current to flow in the LEDs D2 to D4.
However, in the LED driving apparatus according to the related art, the transformer has an advantage in which it electrically separates the primary side and the secondary side from each other; however, the transformer has large volume and a high cost.
In addition, as the smoothing capacitor, a high capacity electrolytic condenser is generally used. However, this high capacity electrolytic condenser has large volume, a high cost, and a lifespan shorter than that of the LED, thereby reducing a lifespan of the LED driving apparatus.
Therefore, in order to solve the above-mentioned problems, a technology for driving an LED without a converter such as a DC-DC converter has been suggested.